reading an "old" php book here.
they are using PHP 3 and I am using 4

did use <?php_track_vars?> so that the variable tracking would be in effect.

but then I got this error:
Warning: <?php_track_vars?> is no longer supported - please use the track_vars INI directive instead.



what do I do then? whats the track_vars INI ?

There are many ways to achieve that, depending on the environment. Take a look here:

http://www.php.net/manual/en/configuration.php